/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.l2j.gameserver.idfactory;

import java.util.BitSet;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;

import net.sf.l2j.gameserver.ThreadPoolManager;
import net.sf.l2j.util.PrimeFinder;

public class BitSetIDFactory extends IdFactory
{
    private static Logger _log = Logger.getLogger(BitSetIDFactory.class.getName());

    private BitSet          _freeIds;
    private AtomicInteger   _freeIdCount;
    private AtomicInteger   _nextFreeId;

	protected class BitSetCapacityCheck implements Runnable
	{
		public void run()
		{
			synchronized (BitSetIDFactory.this)
			{
				if (reachingBitSetCapacity())
					increaseBitSetCapacity();
			}
		}
	}

    protected BitSetIDFactory()
    {
        super();
		synchronized(BitSetIDFactory.class)
		{
			ThreadPoolManager.getInstance().scheduleGeneralAtFixedRate(new BitSetCapacityCheck(), 30000, 30000);
			initialize();
		}
        _log.info("IDFactory: "+ _freeIds.size() + " id's available.");
    }

    public void initialize()
    {
        try
        {
            _freeIds = new BitSet(PrimeFinder.nextPrime(100000));
            _freeIds.clear();
            _freeIdCount = new AtomicInteger(FREE_OBJECT_ID_SIZE);

            for (int usedObjectId : extractUsedObjectIDTable())
            {
                int objectID = usedObjectId - FIRST_OID;
                if (objectID < 0)
                {
                    _log.warning("Object ID " + usedObjectId + " in DB is less than minimum ID of " + FIRST_OID);
                    continue;
                }
                _freeIds.set(usedObjectId - FIRST_OID);
                _freeIdCount.decrementAndGet();
            }

            _nextFreeId = new AtomicInteger(_freeIds.nextClearBit(0));
            _initialized = true;
        }
        catch (Exception e)
        {
            _initialized = false;
            _log.log(Level.SEVERE, "BitSet ID Factory could not be initialized correctly: " + e.getMessage(), e);
        }
    }

    @Override
	public synchronized void releaseId(int objectID)
    {
        if ((objectID - FIRST_OID) > -1)
        {
            _freeIds.clear(objectID - FIRST_OID);
            _freeIdCount.incrementAndGet();
        }
        else
            _log.warning("BitSet ID Factory: release objectID "+objectID+" failed (< "+FIRST_OID+")");
    }

    @Override
	public synchronized int getNextId()
    {
        int newID = _nextFreeId.get();
        _freeIds.set(newID);
        _freeIdCount.decrementAndGet();

        int nextFree = _freeIds.nextClearBit(newID);

        if (nextFree < 0)
            nextFree = _freeIds.nextClearBit(0);
        
        if (nextFree < 0)
        {
            if (_freeIds.size() < FREE_OBJECT_ID_SIZE)
                increaseBitSetCapacity();
            else
                throw new NullPointerException("Ran out of valid Id's.");
        }

        _nextFreeId.set(nextFree);

        return newID + FIRST_OID;
    }

    @Override
	public synchronized int size()
    {
        return _freeIdCount.get();
    }

    protected synchronized int usedIdCount()
    {
        return (size() - FIRST_OID);
    }

    protected synchronized boolean reachingBitSetCapacity()
    {
        return PrimeFinder.nextPrime(usedIdCount() * 11 / 10) > _freeIds.size();
    }

    protected synchronized void increaseBitSetCapacity()
    {
        BitSet newBitSet = new BitSet(PrimeFinder.nextPrime(usedIdCount() * 11 / 10));
        newBitSet.or(_freeIds);
        _freeIds = newBitSet;
    }
}